1. Field of the Invention
The present invention relates to a method used in a communication device in a wireless communication system, and more particularly, to a method of device discovery in a wireless communication system.
2. Description of the Prior Art
In many communication systems, there are usually at least one kind of nodes serving for central control of radio resource and other kinds of nodes serving for user usage by means of connecting at least a serving node. In 3GPP LTE system of wireless communication system, for example, the mentioned nodes serving for central control are eNBs, relay nodes, radio remote heads (RRH), remote antennas, base stations, etc. Those nodes serving for user usage can be UEs, mobile stations, handsets, user devices, machine type devices (i.e. having capability of communicating with other devices without users), etc.
New direct communications between two user devices are different from conventional communication through eNB. This kind of device-to-device communication is new in wireless communication systems, and there is few information so far. Some similar but different behaviors could be found in Bluetooth and WiFi. However, for those skilled in the art should know these two systems are different from communication systems with central control, e.g. LTE, LTE-Advanced, WCDMA, HSPA, WiMAX, etc. In other words, in current wireless communication systems with central control, there is no mechanism yet for device discovery between two communication devices (i.e. two UEs).